Columbia University Medical Center
NewYork-Presbyterian Hospital The University Hospital of Columbia and Cornell

Ask the Experts


I haven’t heard of negative air ionization therapy before. What is it?

Answered by: Michael Terman

Negative ions are naturally occurring charged air particles that are always circulating in the environment around you.

Summer air, in contrast to winter air, is highly concentrated with negative ions. The negative ion machines we use are designed to mimic summer-like conditions by supplementing the sparse winter ion supply.

We are finding that this evokes beneficial mood effects. Although the ions emitted from the machines are not perceptible to your senses, studies have indicated clear improvement in patients with winter depression (the method has yet to be tested for other kinds of depression).

The method does have an interesting precedent, in that many electronic air purifiers utilize negative ion technology. However, don’t expect your air purifier to deliver antidepressant effects—most often, the dose would be far too low, and we are evaluating special apparatus for this purpose.

Michael Terman, Ph.D.

Professor, Dept. of Psychiatry

Dr. Terman is Professor of Clinical Psychology in Psychiatry at the College of Physicians & Surgeons. He heads the Center for Light Treatment and Biological Rhythms at Columbia Presbyterian Medical Center and the Clinical Chronobiology Program at New York State Psychiatric Institute.

His fields of interest include depression, sleep, clinical chronobiology, photobiology, melatonin, instrumentation, psychiatric diagnosis and assessment. He was graduated from Columbia College in 1964 and received a doctorate in physiological psychology from Brown University in 1968. With his career-long c...
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